1. Field of the Invention
The present invention relates to a method and system for measuring the sharpness quality of video data and, in particular, to a method and system for assessing the sharpness quality of pictures without referring to the source video data.
2. Description of the Related Art
It is the ultimate goal of video experts to provide most perceptually appealing video images to viewers. One way to determine whether a resulting image quality is good or poor is to ask a panel of viewers to watch certain video sequences and to give their opinions. Another way to analyze video sequences is to provide an automated mechanism to evaluate the excellence or the degradation of the video quality. Various metrics are used, i.e., sharpness, blocking, ringing, clipping, noise, contrast, and temporal impairments to evaluate the overall video quality measure. In particular, the perception of sharpness is related to the clarity of detail and edge definition of an image. The relative sharpness of an image can be measured, in the spatial domain, by the definition of edges in comparison to a reference image; or, in the transformed domain, by the difference in high frequency energy associated with edges and fine details, also with respect to the reference. These are the main two approaches to sharpness measurement, i.e., using either frequency domain information or spatial domain information.
A common approach to measuring the picture quality of video data is to make a comparison between the processed image and the unprocessed source images. However, utilizing the original video as a reference is not applicable to in-service quality monitoring and the development of a continuous quality-control system. Accordingly, the present invention proposes an objective quality assessment using the video sharpness metric to evaluate the objective quality of pictures without utilizing the source data.